TAMR is expected to be one of the future generations of magnetic recording technologies that will enable recording at ˜1-10 Tb/in2 data densities. TAMR involves raising the temperature of media grains in a magnetic medium to near its Curie temperature where both of its coercivity and perpendicular anisotropy are significantly reduced and magnetic writing becomes easier to achieve even with weak write fields characteristic of small write heads in high recording density schemes. In TAMR, optical power from a light source mounted behind the recording head is transported by a waveguide and then converted into localized heating in a recording medium during a write process to temporarily reduce the field needed to switch the magnetizations of the medium grains. Thus, with a sharp temperature gradient of TAMR acting alone or in combination with a high magnetic field gradient, data storage density can be further improved with respect to current state of the art recording technology.
In FIG. 1a, an example of TAMR optical architecture is shown wherein laser light 8 from a laser diode (LD) 2 mounted on a slider by an end-fire butt coupling 3 is coupled to a waveguide and directed toward an ABS 7-7. A typical waveguide has a first S1 section 4 adjoining the laser diode, a tapered middle S2 section 5, and a narrow end S3 section 6 adjoining the ABS. The y-axis represents the down-track direction and the x-axis is the cross-track direction.
Referring to FIG. 1b, light energy 8 in the waveguide is further coupled to a plasmon generator (PG) micro structure 13 formed between waveguide section 6 and main pole 12. The waveguide is formed on a dielectric (cladding) layer 1 which also contains a read head sensor 11. The cladding layer is formed on a slider 10. The plasmon generator terminates at the ABS and confines plasmon energy 8a to a tiny optical spot 9s on the magnetic medium 9 thereby heating magnetic grains in the medium during a write process. Current technology uses TM LD light with a wavelength near 800 nm. Waveguide light is propagated toward the ABS in a TM polarization mode so that the surface plasmon of the PG can be excited through efficient coupling with the waveguide.
In FIG. 2, a cross-section of the waveguide S3 section 6 is depicted along the plane 45-45 in FIG. 1a. Typically, the S3 section has a rectangular shape with a width a in a cross-track direction and a height or thickness b in the down-track direction.
Although 1 Tb/in2 areal density has been achieved with TAMR, the TAMR head suffers from a short lifetime which has been attributed to resistive heating in the head structure that degrades materials such as Au in the plasmon generator, alumina in the surrounding cladding layer, and FeCo and NiFe typically found in the writer pole. Although resistive heating may be reduced somewhat by designing an improved waveguide alignment scheme so that less power is required from the LD, substantial improvement in technology is still needed from other parts of the light architecture in the slider assembly. Therefore, it is important to optimize all aspects of the light architecture in order to fabricate a TAMR head with a substantial increase in lifetime that is required for commercial products.